The molecular structure of 1,1,1-trimethoxyethane in the gas phase as determined by electron diffraction, molecular mechanics calculations and vibratio

Abstract

The structure of 1,1,1-trimethoxyethane has been studied by electron diffraction in the gas phase. Although this technique cannot discriminate between a GGG (point symmetry C 3) and a TGG ( C 1) conformation, vibrational spectra indicate that in the gas phase the C 1 conformer is predominant. Constraints necessary for a satisfactory leastsquares refinement were obtained from molecular mechanics calculations. The molecular geometry as obtained from r α-refinements is as follows ( r g distances, r α angles; standard deviations in parentheses): r(C-O central = 1.398 (6) Å, r(C-O) terminal = 1.431(6)Å, r(C-C) = 1.527 (6) Å, r(C-H) = 1.114 (1) Å, ∠(C-O-C) = 114.0 (4)°, ∠(O-C-H) = 110.7 (4)°; the C-C-O and O-C-0 angles around the central carbon range between 106.6° and 113.1°.